Multi-carrier arrangement for high speed data

ABSTRACT

The system and method of the present invention uses a plurality of carriers by assigning user terminals to the plurality of carriers so that a minimum grade of service is met and so that throughput is maximized. Each serviced user terminal reports the channel quality of each of a plurality of carriers to a servicing base station(s). The reported channel qualities are then converted to maximum supported data rates for each of the user terminals and each of the carriers. These data rates are then used to allocate data service levels and data rates for each of the user terminals so that a minimum grade of service is met for each of the user terminals. Forward link transmissions, e.g., frames/data packets carried on forward channels (F-CHs), are then constructed and transmitted to meet the allocations.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority pursuant to 35 U.S.C. Sec 119(e)to U.S. Provisional Application Ser. No. 60/177,093, filed Jan. 20,2000, which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates generally to cellular wirelesscommunication networks; and more particularly to the transmission ofvoice communications and data communications in such a cellular wirelesscommunication network.

2. Related Art

Wireless networks are well known. Cellular wireless networks supportwireless communication services in many populated areas of the world.Satellite wireless networks are known to support wireless communicationservices across most surface areas of the Earth. While wireless networkswere initially constructed to service voice communications, they are nowcalled upon to support data communications as well.

The demand for data communication services has exploded with theacceptance and widespread use of the Internet. While data communicationshave historically been serviced via wired connections, wireless usersare now demanding that their wireless units also support datacommunications. Many wireless subscribers now expect to be able to“surf” the Internet, access their email, and perform other datacommunication activities using their cellular phones, wireless personaldata assistants, wirelessly linked notebook computers, and/or otherwireless devices. The demand for wireless network data communicationswill only increase with time. Thus, wireless networks are currentlybeing created/modified to service these burgeoning data communicationdemands.

Significant performance issues exist when using a wireless network toservice data communications. Wireless networks were initially designedto service the well-defined requirements of voice communications.Generally speaking, voice communications require a sustained bandwidthwith minimum signal-to-noise ratio (SNR) and continuity requirements.Data communications, on the other hand, have very different performancerequirements. Data communications are typically bursty, discontinuous,and may require a relatively high bandwidth during their activeportions. To understand the difficulties in servicing datacommunications within a wireless network, consider the structure andoperation of a cellular wireless network.

Cellular wireless networks include a “network infrastructure” thatwirelessly communicates with user terminals within a respective servicecoverage area. The network infrastructure typically includes a pluralityof base stations dispersed throughout the service coverage area, each ofwhich supports wireless communications within a respective cell (or setof sectors). The base stations couple to base station controllers(BSCs), with each BSC serving a plurality of base stations. Each BSCcouples to a mobile switching center (MSC). Each BSC also typicallydirectly or indirectly couples to the Internet.

In operation, a user terminal communicates with one (or more) of thebase stations. A BSC coupled to the serving base station routes voicecommunications between the MSC and the serving base station. The MSCroutes the voice communication to another MSC or to the public switchedtelephone network (PSTN). BSCs route data communications between aservicing base station and a packet data network that may couple to theInternet.

The wireless link between the base station and the user terminal isdefined by one of a plurality of operating standards, e.g., AMPS, TDMA,CDMA, GSM, etc. These operating standards, as well as new 3G and 4Goperating standards define the manner in which the wireless link may beallocated, setup, serviced and torn down. These operating standards mustset forth operations that will be satisfactory in servicing both voiceand data communications.

The wireless network infrastructure must support both low bit rate voicecommunications and the higher bit rate data communications. Moreparticularly, the network infrastructure must transmit low bit rate,delay sensitive voice communications together with high data rate, delaytolerant rate data communications. While voice communications typicallyhave a long hold time, e.g., remain active for longer than two minuteson the average, high data rate/delay tolerant data communications arebursty and are active only sporadically. As contrasted to the channelallocation requirements of voice communications, channels must befrequently allocated and deallocated to the data communication in orderto avoid wasting spectrum. Such allocation and deallocation of channelsto the data communications consumes significant overhead.

To increase throughput of conventional cellular wireless networks, theallocated frequency spectrum is oftentimes subdivided into a pluralityof sub-spectrums, each of which is serviced by a respective carrier.With such a subdivision, the number of user terminals that may beserviced increases relative to the number that may be serviced by asingle carrier. Further, multicarrier systems are less sensitive todispersion and frequency selective fading. Thus, gains are achieved insystems of this type by servicing a greater number of user terminals atany given time. Further, the overhead consumed inallocating/deallocating channels significantly may also decrease in asystem of this type since a greater number of user terminals may beserviced at any one time. However, the bandwidth available forcommunications on each carrier is less than it would be for a singlecarrier using the full spectrum. Thus, the gains achieved in reducingallocation/deallocation overhead are offset by reduced throughput.

It would therefore be desirable to provide a communication system thatefficiently uses a plurality of carriers to service communications withminimal waste of spectral capacity. Further, it would also be desirableto provide a communication system that services both delay sensitive lowbit rate voice communications and delay tolerant data communicationsupon a plurality of carriers without requiring significant additionaloverhead resources.

SUMMARY OF THE INVENTION

The system and method of the present invention efficiently uses aplurality of carriers by assigning user terminals to the plurality ofcarriers so that a minimum grade of service is met and so thatthroughput is maximized. To accomplish these goals, each serviced userterminal reports the channel quality of each of the plurality ofcarriers to a servicing base station(s). The reported channel qualitiesmay then be converted to maximum supported data rates for each of theuser terminals and each of the carriers. These data rates are then usedto allocate data service levels and data rates for each of the userterminals so that a minimum grade of service is met for each of the userterminals. Forward link transmissions, e.g., frames/data packets carriedon forward channels (F-CHs), are then constructed and transmitted tomeet the allocations. With assignments made in this fashion, throughputacross the multiple carriers is maximized.

According to one aspect of the present invention, each carrier supportsa different maximum data rate per user at any given time and includes ascheduler that assigns a data rate allocation for each carrier based oncriteria. The criteria of optimizing total throughput is achieved byminimizing the number of frames being used to satisfy the transmissionneeds of all the users. In this fashion, minimum service levels are metand throughput is maximized.

In one embodiment of the present invention, a Time Division Multiplexed(TDM) superframe/frame structure is employed to carry data and voicecommunications on the F-CHs. This superframe/frame structure isoptimized for servicing both delay tolerant, high data rate datatransmissions, and delay intolerant, fixed rate voice transmissions. TheTDM frame structure of the present invention supports flexible framingof transmissions that include both the lower data rate, delay intolerantvoice communications as well as the delay tolerant higher data rate datacommunications using sub-framing operations. Thus, the system and methodof the present invention provides significant benefits for both datacommunication only wireless traffic and for a combination of voicecommunication and data communication wireless traffic. This TDM framestructure may include a self-indication of its contents such that userterminals may determine whether the TDM frame carries its voice or datacommunications via a simple inspection of the TDM frame itself. Withthis structure, any overhead that was previously required toallocate/deallocate channels is no longer consumed.

The TDM frame structure of the present invention employs data ratematching so that different data rates may be supported for differentuser terminals sharing the TDM frame structure. When used on the forwardlink, a base station selects data rates for each of a plurality ofserviced user terminals based upon the channel qualities of the F-CHsreported by the user terminals for the plurality of carriers. Then, thebase station/network infrastructure constructs a plurality ofsuperframes to service required voice and data communications on theplurality of F-CHs for a given time period such that sufficient servicelevels are met.

Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of the preferred embodiment is consideredin conjunction with the following drawings, in which:

FIG. 1A is a system diagram illustrating a portion of a cellularwireless network constructed according to the present invention;

FIG. 1B is a block diagram illustrating the structure of adjacentcarriers upon which high speed data frames are modulated according tothe present invention;

FIG. 2 is a logic diagram illustrating operation according to thepresent invention in allocating voice communications and datacommunications to a plurality of carriers;

FIG. 3 is a block diagram illustrating the structure of superframes andhigh speed data frames according to the present invention;

FIG. 4 is a block diagram illustrating the structure of a packetaccording to the present invention that is transmitted on a carrier;

FIG. 5 is a logic diagram illustrating operation according to thepresent invention in constructing a plurality of superframes, each ofwhich will be carried upon a separate carrier during a common timeinterval;

FIG. 6 is a block diagram showing an example of an apparatus forgenerating and processing the superframe structure of the invention fora single carrier;

FIG. 7 is a block diagram showing an example of an apparatus forgenerating three superframe structures according to the presentinvention, each of which is carried upon a separate carrier andtransmitted during a common time interval;

FIG. 8 is a block diagram illustrating a base station constructedaccording to the present invention; and

FIG. 9 is a block diagram illustrating a user terminal constructedaccording to the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A is a system diagram illustrating a portion of a cellular system100 in which a base station 102 services a plurality of user terminals106-122 on a plurality of carriers corresponding to a plurality offorward channels (F-CHs) according to the present invention. Thecellular system 100 infrastructure shown includes a base station 102 anda network infrastructure 104. These components are generally known andwill be described only as they relate to the teachings of the presentinvention. The cellular system 100 operates according to a CDMA standardthat has been modified according to the present invention, e.g., IS-95B,IS-2000, 3GPP, W-CDMA, or another CDMA standard that has been modifiedaccording to the operations described herein. In particular, the highspeed data (HSD) 1×EV standard data only (DO), the HSD 1×EV standarddata and voice (DV), and the 3GPP HSD standard may operate according tosome of the aspects of the present invention.

The base station 102 provides wireless service within a correspondinggeographic area (e.g., cell or sector(s)) on the plurality of carriers.The base station 102 establishes a plurality of forward links and atleast one reverse link with the user terminals 106-122. Once these linksare established, the base station 102 transmits voice communications anddata communications to the user terminals 106-122 on the plurality ofF-CHs. Likewise, the user terminals 106-122 transmit voicecommunications and data communications to the base station 102 on thereverse link(s).

Some of the user terminals (e.g., voice terminals 118, 120 and 122)service only voice communications. Alternatively, other of the userterminals (e.g., data terminal 112, vending machine 114 and credit cardterminal 116) service only data communications. Further, at least someof these users terminals (e.g., desktop computer 106, laptop computer108, and wearable computer 110) service both voice communications anddata communications.

Each of the F-CHs is carried upon a respective carrier, e.g., Carrier 1,Carrier 2, Carrier 3, etc. In an embodiment that will be describedherein, the carriers are adjacent to one another in frequency. However,adjacency of the carriers is not a requirement of the present invention.Each of these F-CHs is shared by a plurality of user terminals in a TimeDomain Multiplexed (TDM) fashion. The base station 102 may service theF-CHs in each of a plurality of sectors, with each sector servicing asubset of the user terminals 106-122.

To accomplish sharing of the F-CHs, each F-CH may use a TDM superframestructure that includes a plurality of frames. This superframe/framestructure flexibly accommodates both voice communications and datacommunications, without adversely impacting the requirements of thevoice communications. Further, this superframe/frame structureefficiently supports data communications without wasting any valuableallocated bandwidth and by fairly allocating the available allocatedbandwidth among the serviced user terminals. This TDM frame structuremay also include one or more indications of its contents that areemployed by the user terminals to determine whether the TDM framestructure includes voice/data for the user terminal and, if so, at whatlocations in the TDM frame the voice/data is located and, optionally, atwhat data rate the voice/data is sent. The user terminal may thenreceive the voice/data based upon this indication.

FIG. 1B is a block diagram illustrating the structure of adjacentcarriers that service F-CHs upon which high speed data frames aremodulated according to the present invention. The structure of FIG. 1Bincludes parallel channels that deliver separate data flowssimultaneously using the superframe/frame structure of the presentinvention. Three such carriers of the multi-carrier are shown, namely,Carrier-1, Carrier-2, and Carrier-3. A characteristic of themulti-carrier is the transmission of data flows on multiple, separatelymodulated carriers. Each carrier has different channel conditions inthat the channel quality, e.g., C/I, for a given subscriber is not thesame for each carrier. Independent/correlated fading arises in eachcarrier during throughput of data flows on the carriers. In other words,each carrier can support a maximum data rate per user that is not thesame for each.

For these reasons, it is desirable to service user terminals on carriersthat are favorable for the user terminal. Further, it is desirable tomanage the operation of each carrier to optimize the operation of thecell/sector serviced by the carriers. For example, it may beadvantageous in some operations to place all voice communications on oneof the carriers, e.g., Carrier-1, and to place data communications onthe other carriers, e.g., Carrier-2 and Carrier-3. Further, with theseoperations, not all of the carriers may be needed at any given time. Toavoid adjacent band interference, it may be desirable to temporarilydiscontinue transmissions on one of the carriers, e.g., Carrier-2, whenit is not required during low loading periods.

FIG. 2 is a logic diagram illustrating operation according to thepresent invention in allocating voice communications and datacommunications to a plurality of carriers. The basestation/infrastructure listens for channel quality indications/data rateindications from a plurality of serviced user terminals (step 202). Aplurality of user terminals serviced by a wireless network receivespilot signals from one or more base stations. In most implementations, apilot signal will be transmitted from each sector of each base stationand received by a plurality of terminals within transmission range.However, in other implementations, at least one base station sectorincludes a plurality of beams, each of which includes a transmittedpilot signal. Based upon measured strengths of received pilot signals,measured interference, and thresholds stored internal to the userterminal, each user terminal reports the C/I ratio(s) for the pilotsignals to a base station servicing its reverse link (step 204).Alternately, the user terminals may calculate a maximum data rate atwhich they could receive data on each of the carriers and report thismaximum data rate as the channel quality indication. The base stationreceives channel quality indications from most, if not all of itsserviced user terminals. Once the period of time expires, operation willproceed from step 204.

With the channel quality indications received from the plurality of userterminals, the base station/network infrastructure determines a datarate that may be supported for each reporting user terminal on eachserviced carrier (step 206) for those terminals that reported a C/I forthe carrier. Next, the base station/next infrastructure organizes theuser terminal maximum data rates according to carrier (step 208). Basedupon the data rates for the user terminals and the carriers, andadditional information regarding required minimum grades of service forthe plurality of user terminals, the base station/network infrastructureallocates frames to maximize multi-carrier throughput (step 212).

For example, each of the user terminals may have a request to receive aminimum bit rate that is to be met in each superframe. Alternately, eachof the user terminals may be guaranteed a certain rate over time. Inallocating packets/frames to the plurality of user terminals, the basestation/network infrastructure meets the minimum grade of servicerequired for each user terminal and also maximizes the multi-carrierthroughput. Further, in this allocation, any packets/frames that are notrequired to meet the minimum grade of service for each user terminal arealso allocated to the user terminals. These allocations may be basedupon respective grades of service, fairness, or another criteria.

Then, based upon the packet/frame allocations, the base station/networkinfrastructure assigns frame locations and data rates on the pluralityof carriers to the user terminals (step 214). Finally, the base stationconstructs and transmits frames on the plurality of carriers accordingto the frame location/data rate assignments. The process is thenrepeated.

In one embodiment of a priority system for assigning packets/frames,certain higher priority users may be assigned more than one availableframe for every one frame assigned to other lower priority users. Thisconcept can be generalized. Classes of service can be defined for theservices supported. A user or terminal could support several (logical)connections with a different service and service class for eachconnection. For example, service classes 1, 2, and 3 could have framesallocated in the ratio of 1:n2:n3. With this allocation, on the average,for every frame assigned to a user in service class 1, n2 frames areassigned to a user in service class 2 and n3 frames are assigned to auser in service class 3.

The scheduling algorithm is intended to maximize aggregate throughputbased on the different data rates that the carriers can handle per userand based on the different classes of service, latency requirements anddifferent data rates that the users require. In this manner, thescheduler (further described with reference to FIG. 7) decides whichuser is to receive information in a frame for a particular carrier byoptimizing the order in which carriers are selected to carrycommunications to the user terminals. The communications to a particularuser terminal can be in any frame on any carrier.

For instance, if only a single user needs to transfer data, then theuser may use a frame from each of the carriers. Such was not possible inconventional TDM structure, in which each user would have to keep usingthe frames for the same carrier. Thus, as compared with conventional TDMstructures that confine users to frames of a single carrier, the maximumdata rate in accordance with the present invention would increase by afactor of N per user, where N represents the total number of carriersavailable.

The assignment of the frames to carriers is based on a calculation ofthe aggregate throughput for all users. The goal is to maximize theaggregate throughput. This will minimize the total number of frames thatneed to be used by the users overall to effect their simultaneoustransmission. The scheduler gives users the ability to share any of theframes in the channels as would result in better optimization of theoverall throughput subject to constraints due to class of servicepriority and latency requirements. That is, to attain the bestthroughput through the channels, the number of frames being used tosatisfy the needs of all the users should be minimized.

The selection of the carrier and the data rate is in accordance withjoint scheduling criteria, whether it be in accordance with fairnesscriteria to give all users the same access or on priority criteria togive certain users more access and maintain certain latencyrequirements. In both cases, a percentage of frames is allocated foreach user. The percentage assigned per user may vary dynamically inresponse to channel conditions and latency constraints.

One example of a scheduling algorithm that maximizes the totalthroughput of all users among all carriers includes a case for a3-carrier and N-terminal arrangement. Each terminal reports the measuredC/I for each carrier. The following matrix of Equation (1) results frommapping the C/I to the data rate R (where the superscript identifies theuser and the subscript identifies the carrier):

For a specific frame interval the scheduler assigns the 3 framesavailable to terminals i, j, k from the N terminals in the system basedon certain criteria. The following aggregate rates are calculated:

Rate (i, j, k)=R₁ ^(i)+R₂ ^(j)+R₃ ^(k)

Rate (i, k, j)=R₁ ^(i)+R₂ ^(k)+R₃ ^(ij)

Rate (j, i, k)=R₁ ^(j)+R₂ ^(i)+R₃ ^(k)

Rate (j, k, i)=R₁ ^(j)+R₂ ^(k)+R₃ ^(i)

Rate (k, i, j)=R₁ ^(k)+R₂ ^(i)+R₃ ^(ij)

Rate (k, j, i)=R₁ ^(k)+R₂ ^(j)+R₃ ^(i)

Where Rate (l, m, n) is the aggregate data rate when user terminals l,m, and n are assigned to carriers 1, 2, and 3, respectively. The ratesare then compared and the maximum aggregate rate R(imax, jmax, kmax)=R₁^(imax)+R₂ ^(jmax)+R₃ ^(kmax) is obtained. The scheduler assigns theterminals imax, jmax and kmax to the carriers 1, 2 and 3 respectively.Data is transmitted to the terminals imax, jmax and kmax at rate R₁^(imax) on carrier 1, R₂ ^(jmax) on carrier 2 and R₃ ^(kmax) on carrier3 respectively. The scheduler maximizes the aggregate data rate for aspecific frame interval. Note that this scheduling is still applicableif multiple frames are assigned to one terminal for a specific frameinterval.

FIG. 3 is a block diagram illustrating the structure of superframes andhigh speed data (HSD) frames according to the present invention that aretransmitted on the plurality of carriers. The superframe structure istransmitted on each of the F-CHs and fits within the other requirementsplaced upon the forward links produced by the base station 102. Inparticular, every 400 ms, the base station 102 transmits a broadcastchannel (BCCH) field. In one embodiment, the BCCH field is only includedon one of the F-CHs. However, in another embodiment, the BCCH field isincluded on each of the F-CHs. In either case, an integer multiple ofthe superframes fits within the timing requirement of the BCCH. Asdescribed herein, each superframe is 20 ms in length and includes 16 HSDframes, each having a duration of 1.25 ms. With this structure, the BCCHfield is transmitted every 400 ms using 8 HSD frames at a data rate of76.8 kbps. Further, every 20th 20 ms superframe will include the BCCHfield. Each 20 ms superframe may include voice communications and/ordata communications.

The superframe structure is shared among a plurality of users servicedon the corresponding F-CH. In some operations, all voice and datacommunications for a single user terminal are carried on a single one ofthe F-CHs. However, in other operations, two or more of the F-CHs carryvoice and/or data communications for a single user terminal. In thissuperframe structure, each superframe includes an integer number offrames. Each of the frames may carry voice communications, datacommunications, or a combination of voice communications and datacommunications organized as packets as described below. The data rate isvariable on a packet-by-packet basis with the data rate chosen for thepacket determined based upon the user terminal(s) being serviced in suchpacket and respective channel quality indications for the userterminal(s), as reported by the user terminal(s). Thus, each superframetypically services a plurality of user terminals at a plurality ofdiffering data rates. Further, each superframe is typically filled withvoice and/or data so that all available spectrum is used.

In a described embodiment of the present invention, the F-CH is aspread-spectrum code division multiplexed channel. The F-CH servicesonly a single user terminal at any given time. As described below, voiceand data users may be time division multiplexed on HSD frames. Toincrease channel throughput, the forward link transmission beingserviced at any given time is modulated with a set of 16 Walsh codesprior to its transmission. Thus, the F-CH typically uses no code sharingto distinguish user terminals in the embodiment and only a single userterminal is serviced on any of the F-CHs at any given instant of time.However, in other embodiments, Walsh code subsets, e.g., 8 Walsh codes,4 Walsh codes, etc., may be used to distinguish user terminals from oneanother so that more than one user terminal is serviced on any of theF-CHs at any given instant of time.

Portions of the frames of the superframe may contain data that isseparately modulated with different Walsh codes so that the particularportion of the superframe/frame is separately received by each serviceduser terminal. An example of such data is power control data, e.g.,power control bits, that are transmitted on the F-CH but are employed tocontrol the transmit power of reverse link transmissions. A plurality ofpower control bits that are intended for a plurality of different userterminals are separately modulated with a plurality of correspondingWalsh codes and transmitted on the F-CH within the superframe/frame thesame time. The user terminals then decode this segment of thesuperframe/frame to receive their individual power control bits.

Because the data throughput requirements placed on the reverse link aresubstantially less than those placed on the forward link, the reverselinks are serviced using conventional reverse link CDMA techniques.According to the present invention, the user terminals report F-CHschannel qualities, e.g., pilot signal strength/interference ratio, ormaximum supportable data rate. Based upon the F-CHs channel qualitiesreported by each user terminal, as well as additional factors, the basestation allocates frames of the F-CHs to the user terminals on theplurality of available carriers.

The size of each superframe is limited by the delay tolerance for thelow latency service (voice communications). Based on the delay tolerance(e.g., 20 ms), an integer number of frames are included to form asuperframe of that same duration. In each superframe, each voicecustomer is allocated only the frames or portions of frames needed todeliver the voice communication. Data communications are assigned to theremaining frames and portions of frames that are not used to carry thevoice communication. Preferably, the voice calls are clustered at thebeginning of the superframe.

FIG. 4 is a block diagram illustrating the structure of a packet 400according to the present invention that carries voice or data. In asimple embodiment of the packet 400, the packet includes one or more HSDframes that are successively transmitted on a F-CH. Each HSD frame is1.25 ms in duration and includes 1536 chips and 8 sub-frames. Eachsubframe includes 192 chips. Each HSD frame includes a pilot signal andpower control bits at the beginning of the HSD frame. The first frame ofthe packet 400 includes a preamble following the pilot signal and powercontrol bits at the beginning of the HSD frame.

Generally speaking, the packet 400 includes a sequential group offrames, e.g., HSD frames that are transmitted on a single carrier. Thepreamble of the packet 400 indicates the contents of the packet 400.Such indication may include an explicit data rate indication, whetherthe packet 400 includes voice or data, and for which user terminal(s)the packet is intended.

The pilot signal is used both for timing purposes and for channelquality estimation. The pilot signal is contained at the beginning ofeach HSD frame 400 and pilot signals among all base stations within aservice area synchronized. User terminals receive the pilot signals and,based upon the strength of the pilot signals received, and thecorresponding interference levels, determine a channel qualityindication. Each user terminal then reports to a base station serving aplurality of channel quality indications, one each for each carrier.These channel quality indication reports, e.g., Pilot StrengthMeasurement Message, are reported to its serving base station on eithera R-TCH or a reverse access/control channel

One indication of channel quality is the carrier-to-interference (C/I)ratio for a respective pilot signal/channel. Thus, in one operationaccording to the present invention, the user terminal reports C/I ratiosfor each pilot signal it measures. Such measuring is done for each ofthe carriers. Such reporting may be limited based upon thresholdsapplied by the user terminal. In an alternate operation, a user terminalwould, instead of reporting the channel quality relating to eachreceived pilot signal, determine a maximum supportable data rate foreach corresponding channel and report the maximum supportable datarate(s) to its serving base station. The base station/networkinfrastructure then uses the reported channel qualities to determinefrom which base station(s) to transmit forward link voice communicationsand/or data communications to the user terminal and at what maximum datarate.

Each HSD frame also includes power control bits (PCBs) that direct userterminals currently serviced by the F-CH to either increase or decreasetheir reverse link transmission power. In the described embodiment, eachHSD frame includes a PCB for each user terminal serviced by the F-CH. Inthis embodiment, the PCBs are punctured on the I & Q branches of theF-CH separately. For each user, a respective power control bit ismodulated by one of 16 Walsh codes. These Walsh encoded outputs are thenfurther modulated by a two times PN spreading code. Thus, with thismodulation type, a maximum of 16 users may be served on the I-branch anda maximum of 16 users may be served on the Q-branch so that the reverselink power control of a total of 32 users per frame and per carrier maybe controlled via the PCB bits.

The preamble includes an explicit data rate indicator (EDRI), a useridentification field, and a voice/data indicator. The EDRI provides anexplicit indication of the data rate for data contained in the packet400. The user identification field identifies user terminal(s) for whomthe data contained in the packet is intended. The voice/data indicatorindicates whether the packet contains data or voice, and may indicatethe relative position(s) of the voice/data within the packet 400. Thepreamble provides information for all of the frames that make up thepacket. The basic preamble information may be repeated a number oftimes, the number of repetitions of the preamble being a function of thedata rate.

FIG. 5 is a logic diagram illustrating operation according to thepresent invention in constructing a plurality of superframes, each ofwhich will be carried upon a separate F-CH during a common timeinterval. As was previously discussed, the superframe has a maximumduration to meet the requirements of the voice calls. Further, thesuperframe includes a plurality of frames. The frames have durations andframing structures appropriate to service the particular data rates, anddata throughput requirements of the system.

Operation commences with identifying each voice user that is to beserviced by the superframes (step 504). As was described with referenceto FIG. 1A, each superframe may service zero, one or more voice userterminals 118, 120, and 122. Thus, voice communication information foreach serviced user terminal, if required, must be included in one (ormore) of the superframes being constructed. With each voice useridentified, the data rate to be supported by each voice user for eachcarrier is determined (step 506). The supported data rate(s) also affecthow the voice user transmissions are assigned to the carriers and howthe voice user transmissions are assigned within the superframe of thecarrier, e.g., user terminals having the same data rate may sharepackets of a common carrier. Thus, if two users share packets of acarrier, a data rate is chosen that is supported by the sharing userterminals. Frame assignments for the voice users are then made for theserviced carriers with voice users being multiplexed to share frameswhen possible (step 508).

After the assignment of frames for the carriers to voice users,allocations to data users are made. As a first step in making thisallocation, the data users are identified (step 510). Then, based uponthe service level requirements for each of the data users, e.g., QOS, IPSQL, etc., a determination is made as to which data users will beallocated frames in the current superframes of the carriers. As wasdescribed with reference to FIG. 1A, each carrier is shared by aplurality of user terminals 106-116, some of which require datacommunications support. Of these user terminals 106-116, a determinationis made as to which, or all, of the user terminals 106-116 will beallocated frames in the superframes being constructed.

Once the data users have been identified and their service requirementshave been determined, the remaining frames of the carriers that were notused for the voice users are allocated to the data users (step 512). Aswas previously discussed, each user terminal may support differing datarates for the differing carriers. The available frames of the carriersare then assigned to these data users based upon their respective datarates and the respective allocations (step 516). As was described, voiceusers and/or data users supporting the same data rates may sharepackets.

With the assignments of the voice users and the variable data rate usersmade, the superframes of the carriers are populated with voice and dataaccording to the assignments of steps 508 and 516 (step 518). Then, thesuperframe is transmitted on the carriers to the users (step 520). Thesteps of FIG. 5 are repeated for each subsequent time periodcorresponding to subsequent superframes.

FIG. 6 is a block diagram showing an example of an apparatus forgenerating and processing the superframe structure of the invention fora single carrier/F-CH. The components illustrated in FIG. 6 would beincluded within a base station that constructs the superframe. While theelements of FIG. 6 are shown as conventional circuit elements, some orall of the functions of these elements may be performed via softwareinstructions by one or more digital processing devices, e.g., digitalsignal processor, micro processor, etc.

Multiplexed voice communications and/or the data communications arereceived by an encoder 604. As was described previously, a superframeincludes voice and/or data communications intended for a plurality ofuser terminals serviced by a F-CH. Thus, all of these voice and/or datacommunications pass through the encoder 604 and are multiplexed suchthat they are inserted into a packet in the proper positions. The orderin which the multiplexed voice and/or data communications enter theencoder 604 depends upon the assigned positions of the voice and/or datacommunications within the packet under construction. Operationsperformed in determining the structure of the superframe were describedin detail with reference to FIG. 5.

The encoder 604 encodes the bit stream that it receives. In oneembodiment, the encoder 604 encodes all received voice and datacommunications using turbo-coding operations. However, otherembodiments, other coding technique(s) are employed. A rate-matchingoperator 606 receives the encoded bit stream from the encoder 604 andperforms repeating and/or puncturing operations to cause its output tobe rate matched.

A channel interleaver 608 receives the output of the rate-matchingoperator 606 and interleaves the received input. The channel interleaver608 produces an interleaved output of its received input and providesthe output to a variable modulator/mapper 610. Depending upon the datarate of the particular frame of the superframe that is being produced,the variable modulator/mapper 610 codes the bit stream according to aparticular coding technique.

A demultiplexor 612 receives the encoded output of the variablemodulator/mapper 610 and demulitiplexes the encoded output to produce 16outputs. These 16 outputs are then coded with a 16×16 set of Walsh codesusing Walsh coder 614. Because a F-CH that carries the superframe isTDM, at any time, the voice communication, or data communication carriedby the F-CH is intended for only one user terminal. The user terminalthen decodes one or more received communications using all 16 of theWalsh codes. Such decoding using all 16 Walsh codes produces asignificantly improved decoded result as compared to coding using asingle Walsh code or subset of the 16 Walsh codes. However, as was alsopreviously described, in another embodiment, subsets of Walsh codescould be used to distinguish users on the F-CH.

The output of the Walsh coder 614 is then summed at summing node 616 andmultiplexed with the encoded pilot signal, EDRI, and PCBs at multiplexor618. The pilot signal, EDRI, and PCB, as has been previously describedwith reference to FIG. 4, are separately constructed and encoded. In thedescribed embodiment, the pilot signal, EDRI, and the PCB are puncturedinto the bit stream produced at summing node 616. Thus, some of thevoice/data bits are lost. However, because of the robust nature of theencoding performed by the encoder 604. This puncturing results in littleor no degradation of performance. However, in another embodiment, thepilot signal, EDRI, and the PCB could be TDM multiplexed with thevoice/data stream so that no voice/data is lost due to puncturing. Theoutput of the multiplexor 618 is then modulated with a complex PNspreading code at modulator 620 to spread the energy of thecommunication across the allocated spectrum. The output of the modulator620 is then transmitted on a corresponding F-CH at a designated carrierfrequency.

FIG. 7 is a block diagram showing an example of an apparatus forgenerating three superframe structures according to the presentinvention, each of which is carried upon a separate carrier andtransmitted during a common time interval. All voice and datacommunications are received by a scheduler/multiplexor 702. Based uponoperations previously described, the scheduler/multiplexor 702 timedivision multiplexes the voice and data communications such that theyare placed within a plurality of TDM superframes/frames. In theembodiment of FIG. 7, three TDM superframes are constructed, each ofwhich will be transmitted on a corresponding F-CH at a correspondingcarrier frequency.

The scheduler/multiplexor 702 provides input to superframe processingelements for each of the three F-CHs, 704, 706, and 708, respectively.Each of these superframe processing elements 704, 706, and 708 includesthe structure previously described. The outputs of these superframeprocessing elements 704, 706, and 708 are provided to modulators 710,712, and 714, that modulate the outputs with Carrier 1, Carrier 2, andCarrier 3, respectively. The outputs of the modulators 710, 712, and714, which form the three F-CHs, are then summed at summing node 716 andtransmitted by an antenna to the serviced user terminals.

FIG. 8 is a block diagram illustrating a base station 802 constructedaccording to the present invention that performs the operationspreviously described herein. The base station 802 supports a CDMAoperating protocol, e.g., IS-95A, IS-95B, IS-2000, and/or various 3G and4G standards, that is, or has been modified to be compatible with theteachings of the present invention. However, in other embodiments, thebase station 802 supports other operating standards.

The base station 802 includes a processor 804, dynamic RAM 806, staticRAM 808, Flash memory, EPROM 810 and at least one data storage device812, such as a hard drive, optical drive, tape drive, etc. Thesecomponents (which may be contained on a peripheral processing card ormodule) intercouple via a local bus 817 and couple to a peripheral bus820 (which may be a back plane) via an interface 818. Various peripheralcards couple to the peripheral bus 820. These peripheral cards include anetwork infrastructure interface card 824, which couples the basestation 802 to the wireless network infrastructure 850. Digitalprocessing cards 826, 828, and 830 couple to Radio Frequency (RF) units832, 834, and 836, respectively. Each of these digital processing cards826, 828, and 830 performs digital processing for a respective sector,e.g., sector 1, sector 2, or sector 3, serviced by the base station 802.Thus, each of the digital processing cards 826, 828, and 830 willperform some or all of processing operations described with reference toFIGS. 6 and 7. The RF units 832, 834, and 836 couple to antennas 842,844, and 846, respectively, and support wireless communication betweenthe base station 802 and user terminals (the structure of which is shownin FIG. 9). The base station 802 may include other cards 840 as well.

Superframe Generation and Transmission Instructions (SGTI) 816 arestored in storage 812. The SGTI 816 are downloaded to the processor 804and/or the DRAM 806 as SGTI 814 for execution by the processor 804.While the SGTI 816 are shown to reside within storage 812 contained inbase station 802, the SGTI 816 may be loaded onto portable media such asmagnetic media, optical media, or electronic media. Further, the SGTI816 may be electronically transmitted from one computer to anotheracross a data communication path. These embodiments of the SGTI are allwithin the spirit and scope of the present invention. Upon execution ofthe SGTI 814, the base station 802 performs operations according to thepresent invention previously described herein in generating andtransmitting superframes. The SGTI 816 may also be partially executed bythe digital processing cards 826, 828, and 830 and/or other componentsof the base station 802. Further, the structure of the base station 802illustrated is only one of many varied base station structures thatcould be operated according to the teachings of the present invention.

FIG. 9 is a block diagram illustrating a user terminal 902 constructedaccording to the present invention that performs the operationspreviously described herein. The user terminal 902 supports a CDMAoperating protocol, e.g., IS-95A, IS-95B, IS-2000, and/or various 3G and4G standards that is, or has been modified to be compatible with theteachings of the present invention. However, in other embodiments, theuser terminal 902 supports other operating standards.

The user terminal 902 includes an RF unit 904, a processor 906, and amemory 908. The RF unit 904 couples to an antenna 905 that may belocated internal or external to the case of the user terminal 902. Theprocessor 906 may be an Application Specific Integrated Circuit (ASIC)or another type of processor that is capable of operating the userterminal 902 according to the present invention. The memory 908 includesboth static and dynamic components, e.g., DRAM, SRAM, ROM, EEPROM, etc.In some embodiments, the memory 908 may be partially or fully containedupon an ASIC that also includes the processor 906. A user interface 910includes a display, a keyboard, a speaker, a microphone, and a datainterface, and may include other user interface components. The RF unit904, the processor 906, the memory 908, and the user interface 910couple via one or more communication buses/links. A battery 912 alsocouples to and powers the RF unit 904, the processor 906, the memory908, and the user interface 910.

Superframe Receipt and Response Instructions (SRRI) 916 are stored inmemory 908. The SRRI 916 are downloaded to the processor 906 as SRRI 914for execution by the processor 906. The SRRI 916 may also be partiallyexecuted by the RF unit 904 in some embodiments. The SRRI 916 may beprogrammed into the user terminal 902 at the time of manufacture, duringa service provisioning operation, such as an over-the-air serviceprovisioning operation, or during a parameter updating operation. Thestructure of the user terminal 902 illustrated is only an example of oneuser terminal structure. Many other varied user terminal structurescould be operated according to the teachings of the present invention.

Upon execution of the SRRI 914, the user terminal 902 performsoperations according to the present invention previously describedherein in receiving packets/superframes according to the presentinvention on the plurality of F-CHs. These operations include decodingportions of the packets/superframes intended for the user terminal 902and responding to a servicing base station, e.g., base station 902, toindicate channel qualities. Operations performed by the user terminal902 in receiving the packets/superframes and extracting intendedcommunications are performed inversely to the techniques described withreference to FIGS. 6 and 7. Additional required operations of receivingand interpreting the preamble and/or primary EDRI and the secondary EDRIare evident based upon the teachings provided herein. Further, other ofthese operations are executed to report channel quality indications ormaximum supportable data rate indications to a base station 902 thatservices a corresponding reverse link.

The invention disclosed herein is susceptible to various modificationsand alternative forms. Specific embodiments therefore have been shown byway of example in the drawings and detailed description. It should beunderstood, however, that the drawings and detailed description theretoare not intended to limit the invention to the particular formdisclosed, but on the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present invention as defined by the claims.

1. A method of operating a base station to transmit communications to aplurality of user terminals on a plurality of carriers, the methodcomprising: for each of the plurality of carriers, receiving channelquality indications from the plurality of user terminals; based upon thechannel quality indications received from the plurality of userterminals, for each of the plurality of carriers, determining a maximumdata rate supportable for each of the user terminals; based upon themaximum data rate supportable for each of the user terminals for each ofthe plurality of carriers, and a minimum quality of service required foreach user terminal, allocating frames in a plurality of superframescorresponding to the plurality of carriers a subsequent communication tothe plurality of user terminals; transmitting the subsequentcommunication to the plurality of user terminals based upon theallocation of frames; and wherein the plurality of superframes aretransmitted on the plurality of carriers and are synchronized in time.2. The method of claim 1, further comprising allocating the plurality offrames to the plurality of user terminals in order to maximizethroughput based upon the constraints of service criteria.
 3. The methodof claim 2, wherein the service criteria are based upon user terminalsubscription levels.
 4. The method of claim 2, wherein the servicecriteria is based upon fairness in resource allocation.
 5. The method ofclaim 1, wherein the subsequent communication includes both voicecommunications and data communications.
 6. The method of claim 1,wherein the base station transmits voice communications and the datacommunications on separate carriers.
 7. The method of claim 5, whereinsuccessive packets of a data communicationare carried on separatecarriers.
 8. The method of claim 5, wherein successive packets of avoice communication are carried on separate carriers.
 9. The method ofclaim 1, wherein: each superframe includes a plurality of frames that istransmitted on one carrier of the plurality of carriers; and a frame ofthe plurality of frames includes a preamble that indicates the contentsof the frame.
 10. The method of claim 1, wherein the base stationtransmits superframes at a frequency that meets a voice communicationrate requirement.
 11. The method of claim 1, further comprising codingat least one superframe with a plurality of Walsh codes prior to itstransmission.
 12. The method of claim 1, wherein at least onesuperframes support both voice communications and data communications.13. The method of claim 1, wherein each superframe includes a pluralityof frames and each frame includes: a pilot signal; and a plurality ofreverse link power control bits intended for the plurality of userterminals.
 14. The method of claim 9, wherein the preamble furtherindicates that the frame carries a voice communication.
 15. The methodof claim 9, wherein the preamble further indicates that the framecarries a data communication.
 16. The method of claim 9, wherein: thepreamble includes a user identifier field; and the user identifier fieldidentifies one or more user terminals for which the frame is intended.17. The method of claim 9, wherein: the preamble includes an explicitdata rate indicator and an identifier, the explicit data rate indicatorindicates a data rate of the frame; and the identifier identifies one ormore user terminals for which the frame is intended.
 18. The method ofclaim 1, further comprising assigning communications for a particularuser terminal on a carrier having a best channel quality indication. 19.The method of claim 1, wherein a superframe of the plurality ofsuperframes supports both voice communications and data communications,and the method further comprises: encoding the data communications ofthe superframe using a first coding algorithm; and encoding the voicecommunications of the superframe using a second coding algorithm that isdifferent from the first coding algorithm.
 20. The method of claim 1,wherein the plurality of superframes are time-aligned when transmittedon the plurality of carriers.
 21. A method of operating a user terminalwithin a wireless communication system to receive communications on aplurality of carriers, the method comprising: receiving a plurality ofpilot signals, wherein each pilot signal corresponds to a carrier of theplurality of carriers; determining a plurality of channel qualityindications, wherein each channel quality indication corresponds to oneof the plurality of carriers; reporting the plurality of channel qualityindications to a serving base station; and receiving a communication ina superframe on on a corresponding carrier of the plurality carriersthat satisfies a minimum quality of service required for the userterminal, wherein receiving the communication includes decoding thesuperframe with a plurality of Walsh codes.
 22. The method of claim 21,wherein the communication includes both a voice communication and a datacommunication.
 23. The method of claim 22, further comprising: receivinga voice communication in a frame of a superframe on a first carrier ofthe plurality of carriers; and receiving a data communication in a flameof a superframe on a second carrier of the plurality of carriers. 24.The method of claim 22, wherein the voice communication and the datacommunication are received on a common carrier.
 25. The method of claim21, wherein the plurality of superframes carried by the plurality ofcarriers arrive synchronized in time.
 26. The method of claim 21,wherein: the communication is received in a a frame of a superframe thatincludes a plurality of frames and that is transmitted on one carrier ofthe plurality of carriers; and the frame includes a preamble thatindicates the contents of the packet.
 27. The method of claim 26,wherein: data communications received in the superframe are encodedusing a first coding algorithm; and voice communications received in thesuperframe are encoded using a second coding algorithm that is differentfrom the first coding algorithm.
 28. The method of claim 21, furthercomprising receiving communications on a carrier having a best channelquality.
 29. A base station that transmits communications to a pluralityof user terminals on a plurality of carriers, the base stationcomprising: an antenna; a Radio Frequency unit coupled to the antenna;and at least one digital processor coupled to the Radio Frequency unitthat executes software instructions causing the base station to: foreach of the plurality of carriers, receive channel quality indicationsfrom the plurality of user terminals; based upon the channel qualityindications received from the plurality of user terminals, for each ofthe plurality of carriers, determine a maximum data rate supportable foreach of the user terminals; based upon the maximum data rate supportablefor each of the user terminals for each of the plurality of carriers,and a minimum quality of service required for each user terminal,allocate frames in a plurality of superframes corresponding to theplurality of carriers in a subsequent communication to the plurality ofuser terminals; transmit the subsequent communication to the pluralityof user terminals based upon the allocation of frames; and wherein theplurality of superframes are transmitted on the plurality of carriersand are synchronized in time.
 30. A user terminal that operates towirelessly receive communications on a plurality of carriers, the userterminal comprising: an antenna; a Radio Frequency unit coupled to theantenna; and a digital processor coupled to the Radio Frequency unitthat executes software instructions causing the user terminal to:receive a plurality of pilot signals, wherein each pilot signalcorresponds to a carrier of the plurality of carriers; determine aplurality of channel quality indications, wherein each channel qualityindication corresponds to one of the plurality of carriers; report theplurality of channel quality indications to a serving base station; andreceive a communication in a superframe on a corresponding carrier ofthe plurality of carriers that satisfies a minimum quality of servicerequired for the user terminal, wherein receiving the communicationincludes decoding the superframe with a plurality of Walsh codes.
 31. Aplurality of software instructions stored on a media that, uponexecution by a base station, cause the base station to transmitcommunications to a plurality of user terminals on a plurality ofcarriers, the plurality of software instructions comprising: a set ofinstructions executed by the base station that cause the base stationto, for each of the plurality of carriers, receive channel qualityindications from the plurality of user terminals; a set of instructionsexecuted by the base station that cause the base station to, based uponthe channel quality indications received from the plurality of userterminals, for each of the plurality of carriers, determine a maximumdata rate supportable for each of the user terminals; a set ofinstructions executed by the base station that cause the base stationto, based upon the maximum data rate supportable for each of the userterminals for each of the plurality of carriers, and a minimum qualityof service required for each user terminal, allocate frames in aplurality of superframes corresponding to the plurality of carriers in asubsequent communication to the plurality of user terminals; and a setof instructions executed by the base station that cause the base stationto transmit the subsequent communication to the plurality of userterminals based upon the allocation of frames such that the plurality ofsuperframes are transmitted on the plurality of carriers and aresynchronized in time.
 32. A plurality of software instructions stored ona media that, upon execution by a user terminal, cause the user terminalto wirelessly receive communications on a plurality of carriers, theplurality of software instructions comprising: a set of instructionsexecuted by the user terminal that cause the user terminal to receive aplurality of pilot signals, wherein each pilot signal corresponds to acarrier of the plurality of carriers; a set of instructions executed bythe user terminal that cause the user terminal to determine a pluralityof channel quality indications, wherein each channel quality indicationcorresponds to one of the plurality of carriers; a set of instructionsexecuted by the user terminal that cause the user terminal to report theplurality of channel quality indications to a serving base station; anda set of instructions executed by the user terminal that cause the userterminal to receive a communication in a superframe on on acorresponding carrier of the plurality of carriers that satisfies aminimum quality of service required for the user terminal, whereinreceiving the communication includes decoding the superframe with aplurality of Walsh codes.